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At least 505 records · Page 28

Intelligent Optimization of the Digital Low Level RF Control System for LANSCE LINAC

The LINAC at the Los Alamos Neutron Science Center (LANSCE) accelerates protons from 750 keV to its final energy at 800 MeV via 48 radio frequency (RF) modules. However, the startup and recovery process of the low-level RF (LLRF) systems, the primary controls for the RF modules, cost significant time for the beam operation, while the process itself is highly prone to human errors. With the new conversion from the analog LLRF (aLLRF) to digital LLRF (dLLRF) system under the recent LANSCE Modernization Project, new approaches with the new dLLRF capabilities can be achieved to address this issue. We propose to develop an intelligent optimization scheme that can significantly lower the downtime caused by the LLRF systems. This directly address the MFR problem statement that asks for “innovative engineering improvements to ancillary systems such as RF and pulsed power that improve reliability, maintainability, and/or performance.”

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High gradient research and facilities at Los Alamos National Laboratory [Slides]

A particle accelerator is a scientific instrument that produces a directional stream of electrically charged particles, usually electrons or protons. The accelerator propels particles to high speeds, close to the speed of light. Historically, accelerators play a crucial role in scientific discovery. Nowadays, accelerators produce particle beams for biomedical and material research, manufacturing, energy technology, and Homeland security.

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Diagnostics for PSR Upgrade

This report discusses the diagnostics upgrade plan for the PSR. The PSR diagnostics under discussion include beam position and phase monitor (BPPM), wirescanners, wall current monitors, bunch shape monitors, laser notchers, and diamond array detectors. Existing diagnostics at the PSR include beam position monitors (BPM), a wirescanner, and a wall current monitor. All existing diagnostics need modernization, as part of the PSR upgrade plan. Meanwhile, we will introduce minor changes to improve the existing setups, which will enhance the performance and the longevity of the diagnostics equipment and components in the upgraded PSR operation. On the other hand, new, advanced, and available diagnostic technologies at a high technology readiness level (TRL) can also be considered for implementation for the PSR upgrade. In this note, we go through all types of diagnostics, introducing their basic principle, operating status, and plans for the PSR upgrade.

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805 Stepped Plan Project Description

The 805 MHz system utilizes 1.25 MW class klystron amplifiers. The Solid-State Amplifier (SSA) technology has been utilized in the SC accelerator technology, but more powerful sources are needed for use in the NC accelerator facilities such as LASNCE. The SSA topologies that are widely used need to be scaled and tested for reliability and operation in a high impact accelerator facility, such as the 805 MHz SCCL in Los Alamos. Operational experience with high power SSA needs to be assessed prior to installation of an SSA unit at LANSCE. The RFE group at LANSCE is looking for collaboration in the development of the Solid-State Amplifier.

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Reverse Engineering Richmond Eyebolts [Slides]

The Richmond Eyebolt Lift Fixture system is used to move older styles of concrete shield blocks here at LANSCE. Blocks can weigh anywhere from 1.8 to 18 tons. It consists of the eyebolt itself and a steel insert that is cast into the block. Eyebolts come in 2-inch or 1&1/2-inch sizes. The lifting capacity of the 1-1/2-inch is 23,000 lbs and the 2-inch is 30,000 lbs.

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Modeling LANSCE Line D and RI Beamlines in Elegant and Impact-T

This technical report describes models in Elegant and Impact-T of two LANSCE high-energy beamlines: LineD and Ring Injection. These two beamlines transport the 800 MeV H- beam from the exit of the 805 MHz Linac to the entrance of the PSR. Computer models of all LANSCE high-energy beamlines exist in Transport but include a limited model of the space charge forces. A motivation for using Elegant as an optional beam dynamics code is that the existing model of the PSR is in Elegant, therefore enabling the modeling of the full beam injection scheme. Also, Elegant is a modern code being used by a large accelerator physics community which makes the calculation results more reliable. The drawback is that Elegant has also a limited space charge force model. Therefore, we have opted to include the Particle-In-Cell (PIC) code Impact-T as an alternate beam dynamics code to verify the Elegant calculations. We will use the new Line D and RI models to study beam halo in the transport leading into the PSR, and to evaluate collimation schemes as part of the PSR upgrade. The new models can also be readily used in support of other LANSCE activities.

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Beam Optics Studies for Larger Beampipe Diameters for the LAMP-PSR

The proposed beampipe diameter increase of the PSR beamlines for the LAMP PSR upgrade is expected decrease beam loss due to tuning errors and misalignment. However, a larger beampipe diameter would require increasing the pole-to-pole gap height within all magnets in the PSR (dipole gap, quadrupole bore, etc.). This would in turn affect the extent and profile of the fringe fields at the ends of the magnets, altering the effective length of the magnets and thus the magnetic optics. In this work, we used the simulation code MAD-X to model the PSR lattice for different beampipe diameters. The results of these simulations will be later used to benchmark particle simulations using the code pyORBIT. The MAD-X simulations are described, and the simulation results are discussed in this technote.

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PARMELA simulation of Line-A beamline

This is a short re-work of the previously accomplished simulations, using PARMELA code package. This exercise was done primarily for increase of fidelity and re-formulating the given task for a different beam dynamics (BD) code. The performed simulations showed very good agreement with the abovementioned simulations and confirm the previously produced results with the BEAMPATH code.

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Improving Longitudinal Impedance of Inductive Inserts

Space charge compensation is essential to keeping the beam inside a ring such as PSR in the desired bunch form. The space charges of the ring will lead to the beam debunching, and the most prominent form of compensation for this is the use of RF to bunch the ring back. It has long been known however, that the impedance presented to the beam by its space charge could be compensated by a passive component. Such a passive component has been in use in PSR since 2000, but upgrading it could greatly improve the capabilities of the PSR. Additionally, the inserts presently used would require updating to match any changes in the beam pipe, both mechanically and to increase the space charge compensation.

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Flow Induced Vibration Studies in Pressurized Helium Gas Cooling Channels

Production of metastable Technetium-99 (Tc-99m), a radioactive tracer that emits gamma rays, is vital to the medical imaging community. Tc-99m is extracted from the decay of Molybdenum-99 (Mo-99) which has a half-life of about 2-3 days. The work presented in this report is part of the NNSA’s mission to produce Mo-99 commercially, within the US, without the use of highly enriched uranium (HEU) in support of nonproliferation and global security. Los Alamos National Laboratory (LANL) is working with NorthStar Medical Radioisotopes (NMR) on their efforts to produce Mo-99 through the irradiation of Mo-100 targets using an electron beam. The NMR target comprises a stack of approximately 60-70 Mo-100 disks with diameter 24 mm and thickness 0.74 mm held in stainless steel laminations, each separated using 0.25 mm thick stainless steel spacers. The symmetric target stack is housed in an Inconel vessel with two Inconel windows on either side. Two electron accelerators are used to produce 40 MeV, 3.16 µA electron beams each that penetrate the Inconel windows and irradiate the Mo-100 disks. Approximately 90% of the total 250 kW beam power is deposited in the NMR target during the irradiation process. During irradiation, pressurized helium gas flows through 0.25 mm thin gaps between the disks cooling the beam window, target disks, disk laminations and spacers. Both NMR and LANL have found during cold testing of the target system (no heat deposition) that the Mo-100 disks undergo significant mass loss and disk breakage due to vibrations induced by the flowing helium gas. The mass loss is not only undesirable due to monetary loss from reduced final quantities of Mo-99, but also due to the hazards associated with radioactive material trapped in the cooling lines and particle filters. The effect of flow rate and target geometry on the flow induced vibrations need to be quantified, and recommendations provided to minimize this mass loss. This work describes LANL’s experimental characterization of the flow induced vibrations and disk mass loss in a reduced scale set-up containing 10 Mo-100 disks. We use high speed imaging, displacement measurements and microphone measurements combined with signal processing to estimate the vibration frequency of each disk. The effect of disk thickness, target fit and duration of testing on the mass loss is described. We find that in the current configuration of NMR targets, the vibrations and mass loss on the first disk are minimized, while those in the adjacent disks are highest. The microphone and high-speed image data show that increased flow rates and increased duration of testing increases vibration frequency and mass loss. The mass loss is due to both disk rotation and back and forth motion. There are visible wear marks on the disks with the highest mass loss. We also note that the current NMR window gap reduces flow induced vibrations compared to the previous smaller gaps. Longer duration testing will provide more data and verification for the findings presented in this report. The work will be continued in FY 24.

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Area-A Options Cost Estimate Report

Five options for re-establishing various configurations of beam to LANSCE Area A were considered. Bottoms up cost estimates to implement three of the options were developed. The two options not costed were considered too complex and too expensive compared with the other options based on their relative benefits to experimental programs at LANSCE.

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LANSCE Accelerator Modernization Project (LAMP) Overview [Slides]

LANSCE is based on a high-current 800 MeV proton accelerator capable of delivering 1 MW of beam power to the central target area. The LANSCE accelerator provides beam simultaneously to 5 separate experimental areas. LANSCE operates with 650 µs RF macro pulses at 120 Hz. Within this macro pulse several different beam timing patterns are utilized. LANSCE also accelerates H + and H – simultaneously. LANSCE celebrated 50 years of beam delivery in 2022.

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Diagnostics for measuring 4D beam matrix [Slides]

Detailed knowledge on the particle distribution in accelerators can strongly benefit machine tuning and understanding of deleterious effects, which degrade beam quality. Properties of the beam downstream the beamline (i.e. 4D beam matrix) depend on beam properties upstream and parameters of the beamline. Measuring 2D x-y beam profile downstream provides limited information about the beam. Multiple measurements at different settings of the beamline (quadrupole scan) may provide enough information to recover original beam profile. Essentially, this concept is similar to tomography, when we need to reconstruct a higher dimension object from multiple low dimension projections.

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Risk-based System Upgrade Planning for AOT-IC [Capstone Project]

The Accelerator Operations and Technology Instrumentation and Controls Group (AOT IC) at the Los Alamos Neutron Science Center (LANSCE) has established a comprehensive risk-based system upgrade planning strategy which has been utilized as a tool to prioritize system upgrade projects for the past several years. A challenge with the current system is that the group often lacks the data to quantify the probability and impact of system failures, so the group often relies instead on qualitative risk assessments as well as evaluations of a potential upgrade project’s alignment with group strategy and vision to prioritize projects. A proposed framework to enable quantitative risk probability and impact assessments has been developed and tested on three pilot systems chosen to broadly represent the types and conditions of equipment used by the group. The proposed framework incorporates availability data gathered from the LANSCE control room logbooks and the LANSCE work control system, as well as a system health evaluation which is conducted from a variety of resources to assess the probability of equipment failure. The impact of system failure is viewed from the perspective of impact on mission and schedule, where spares status, system documentation status, and the functional distribution of deployed systems are used to quantify these impacts.

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Risk-based System Upgrade Planning for AOT-IC Presentation [Slides]

The number of deployed systems and different HW/SW form factors makes it difficult to maintain a complete understanding of their health which leads to a reduced level of certainty when assessing risk and trying to prioritize system upgrade efforts. AOT-IC must constantly plan and execute system upgrade and replacement projects to ensure the longevity of the control system. There are many more projects needed than the group can realistically accomplish given schedule and resource constraints. The group must prioritize their upgrade projects to choose only the highest priority projects to execute each year. Currently plans upgrade and replacement projects based on alignment with mission needs, group vision, resource availability, and qualitative risk assessments based on SME estimates. The group maintains a risk register. This is useful as a tool for shaping strategic planning but currently lacks the quantitative data and process needed to generate accurate risk assessments.

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